JPH09152381A - Load converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small load converter for simplifying the cutting work and facilitating the pasting work of strain gauge. SOLUTION: A columnar metal block is cut at the upper and lower parts while directing the central part inward thus forming recesses 14, 15 while leaving load transmission rings 12, 13 on the circumference. The intermediate part is further cut from opposite directions over a width reaching the recesses 14, 15 to form a plate part 11 in the center. Among joints 16, 17, 18, 19 between the plate part 11 and upper/lower load transmission rings 12, 13, upper and lower joints 17, 18 opposing obliquely are separated and the plate part 11 is coupled with upper/lower load transmission rings 12, 13 through the joints 16, 19, respectively. Substantially hourglass type strip-off part 20 is formed in the center of plate part 11 and four flexures 21 are formed around the strip-off part 20 thus providing a Roberval mechanism. A strain gauge 22 is applied to the outer surface of each flexure 21 and a lead wire is led out therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load transducer having a novel structure for measuring a load.

[0002]

2. Description of the Related Art A load cell is used as one method for measuring load, but when measuring load,
Load cells are often machined integrally from a rectangular metal block. For example, as shown in FIG. 6, a plate-shaped metal block 1 is cut and cut, a substantially gourd-shaped cut-out portion 2 is formed in the central portion, and a measuring portion 4 having a Roberval mechanism having a flexure 3 is provided. The load transmission levers 5 and 6 are formed on the upper and lower sides, and the strain gauge 7 is attached to the flexure 3 of the Roberval mechanism and used as a load cell.

[0003]

However, in this case, the milling machine is mainly used to process the rectangular metal block 1 into a predetermined shape, and a simple lathe cannot be used, which is extremely troublesome. There is also a processing time, and the cost is high. Further, the thickness of the flexure 3 can be measured only by inserting a caliper from the side surface, and there is a problem that the thickness control of the flexure 3 is insufficient. Further, when the strain gauge 7 is attached to the flexure 3, it is necessary to insert the strain gauge 7 through the gap, and it is not easy to confirm the attached state in detail even after completion. .

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a load transducer that is relatively easy to cut, can be miniaturized, and can be easily attached with a strain gauge.

[0005]

In order to achieve the above object, a load converter according to the present invention is configured such that a central portion of both upper and lower surfaces of a metal block is cut inward to form a concave portion, and the metal block is formed. A load transmission ring that surrounds the upper and lower recesses by cutting inward from two opposite directions of the middle part of the metal block, and a plate portion located at the center of the metal block. Of the upper and lower load transfer rings, and two upper and lower connecting portions of the plate portion and the upper and lower load transmission rings are separated from each other by diagonally opposing the upper and lower connecting portions. The upper and lower load transmission rings are connected to each other by one connecting portion, and a Roberval mechanism having four flexures is provided by removing the plate portion, and a strain gauge is attached to the flexure portion. Top and bottom loads The load applied between the transfer ring and transmitted to the Roberval mechanism of the plate body portion, and measuring the load by the deformation of the flexure is detected by the strain gauge.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is an exploded perspective view of a load converter of the first embodiment, FIG. 2 is a vertical cross-sectional view, and FIG. 3 is a plan view of a measuring portion, the measuring portion is a central plate body portion 11 and an upper load transfer ring. 12 and the load transfer ring 13 at the lower part.

These are cut from a cylindrical metal block such as steel or aluminum with a lathe and a milling machine, and the upper and lower parts are cut with the central part facing inward to form recesses 14 and 15. While leaving the portions to be the load transmitting rings 12 and 13 around, and cutting the intermediate portion from the two opposite directions over the width reaching the recesses 14 and 15, the plate body portion 11 is formed in the central portion and Of the upper and lower two connecting portions 16, 17, 18, 19 of the body portion 11 and the upper and lower load transmitting rings 12, 13, the upper and lower connecting portions 17, 18 diagonally opposed to each other are separated, The plate portion 11 includes upper and lower load transmission rings 12 and 13 and one connecting portion 1 each.
6 and 19 are connected.

A substantially gourd-shaped stripping portion 20 formed by joining two circles is formed in the central portion of the plate portion 11, and a total of four flexures 21 are provided around the stripping portion 20.
Is formed and a Roberval mechanism is provided. A strain gauge 22 is attached to the outer surface or the inner surface of each flexure 21, and a lead wire (not shown) is drawn to the outside.

Further, the load transfer rings 12 and 13 are provided with base plates 23 and 24, respectively, in which convex portions 25 and 24 are provided at their central portions.
26 is fitted in the recesses 14 and 15 and is fixed to the load transmission rings 12 and 13 by screws (not shown). The base plates 23 and 24 have bolt holes 2 for transmitting loads.
7 are provided. In addition, 28 and 29 are screw holes.

In use, when a load is applied to the base plate 23 via bolts, the flexure 21 of the plate body 11 having the Roberval mechanism is deformed via the load transmission ring 12, and this deformation is attached to the flexure 21. It is possible to measure the load which is detected by the attached strain gauge 22 and applied through an electric circuit (not shown).

FIG. 4 shows a second embodiment and is a sectional view of the load converter which is hermetically sealed to protect it from moisture and the like. The same reference numerals as those in the first embodiment indicate members having the same function. The circumference of the load converter is hermetically sealed by a cylindrical cover 31, and is connected to the measuring unit through upper and lower flexible bellows 32 and 33 so that the force from the cover 31 is not transmitted.

A load transmission portion 34 having a bolt hole 27 is screwed into the base plate 23, and the base plate 24 is a base 31 of the cover 31.
It is connected to the load transmission ring 13 via a. The bellows 32 seals between the upper portion 31b of the cover 31 and the load transmitting portion 34, and the bellows 33 seals the base portion 3 of the cover 31.
The circular hole of 1a is sealed. A through hole 35 is provided in the center of the plate portion 11 in the vertical direction, and a connecting rod 36 that connects the bellows 32 and 33 is inserted through the through hole 35. In addition, 37 is a ventilation hole provided in the base plate 24.

As a result, since the cover 31 is hermetically sealed, a pressure difference is generated between the inside and the outside of the cover 31 due to changes in atmospheric pressure and temperature. Even if the pressure difference moves the bellows 32, 33, the bellows Since 32 and 33 are connected by a connecting rod 36, the bellows 32 and 33 are connected.
It is possible to prevent the forces applied to the force from being canceled and the deformation of the bellows 32 and 33 to appear as a minute change in the load.

Since the connecting rod 36 in this case is inserted into the through hole 35 of the plate portion 11, the space can be skillfully utilized and the connecting rod 36 does not become large.

In the above-mentioned embodiment, the cutting process was carried out based on the cylindrical metal block, but it can also be formed from the prismatic metal block. In this case, the upper and lower load transfer rings are square frame-shaped. Therefore, the base plate also has a suitable shape. In addition, the stripping portion 20 provided on the plate body portion 11 may be a simple circle instead of a substantially gourd shape.

[0016]

As described above, the load converter according to the present invention has the following effects.

(1) Since the load transmission ring is not in the same plane as the plate portion, it is possible to bring them close to each other, thereby increasing the rigidity and increasing the Roberval value without increasing the height. .

(2) When it is formed from a cylindrical metal block, the processing is easy because it is mainly performed by a lathe, and the processing time can be shortened.

(3) Since the thickness of the flexure can be measured by the macrometer before mounting the base plate, the accuracy is improved by about one digit as compared with the conventional caliper measurement, and the thickness of the flexure can be accurately adjusted.

(4) The strain gauge can be pasted easily and accurately because the pasting point is exposed in the vertical direction, and the pasting state can be confirmed by a microscope or the like.

(5) Since the board provided with the electric circuit can be housed in the space portions on both sides of the plate body, it becomes possible to perform an electric treatment such as amplification in the vicinity of the strain gauge, and the electric stability is improved. improves.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a first embodiment.

FIG. 2 is a longitudinal sectional view.

FIG. 3 is a plan view of a measurement unit.

FIG. 4 is a sectional view of the second embodiment.

FIG. 5 is a plan view of a measurement unit.

FIG. 6 is a perspective view of a conventional example.

[Explanation of symbols]

 11 Plates 12, 13 Load Transmission Rings 14, 15 Recesses 16, 19 Connections 20 Stripping 21 Flexure 22 Strain Gauge 23, 24 Base 31 Cover 32, 33 Bellows 35 Through Hole 36 Connecting Rod

Claims (6)

[Claims] 1. A width which reaches the both recesses inward from two opposite directions of an intermediate portion of the metal block by cutting the center portions of the upper and lower surfaces of the metal block inward. Forming a load transmission ring surrounding the upper and lower recesses and a plate portion located in the central portion of the metal block by cutting over the upper and lower portions, and the plate portion and the upper and lower load transmission rings are provided on the upper and lower sides, respectively. Of the individual connecting parts, the plate parts and the upper and lower load transfer rings are connected by one connecting part respectively by separating the connecting parts that are diagonally opposed to each other one above and one below, and the plate is connected to each other. A Roberval mechanism having four flexures is provided by peeling the body off, a strain gauge is attached to the flexure, and the load applied between the upper and lower load transfer rings is applied to the Roberval mechanism of the plate body. Communicate A load converter, wherein a load is measured by detecting the deformation of the flexure with the strain gauge. 2. The load converter according to claim 1, wherein the plate portion is cut out into a substantially gourd shape in which two circles are arranged side by side. 3. The load converter according to claim 1, wherein a base plate is attached to the upper and lower load transmission rings. 4. The load transmission ring, the plate body portion, and the base plate are surrounded by a cover, and the load transmission ring, the plate body portion, and the base plate are connected to each other through upper and lower bellows. The load converter according to claim 3, wherein the inside of the cover is sealed. 5. The load converter according to claim 4, wherein the upper and lower bellows are connected by a connecting rod. 6. The load converter according to claim 5, wherein the connecting rod is inserted through a through hole provided along the vertical line at the center of the plate body portion.